| 1 | /* |
| 2 | * arch/xtensa/kernel/signal.c |
| 3 | * |
| 4 | * Default platform functions. |
| 5 | * |
| 6 | * This file is subject to the terms and conditions of the GNU General Public |
| 7 | * License. See the file "COPYING" in the main directory of this archive |
| 8 | * for more details. |
| 9 | * |
| 10 | * Copyright (C) 2005, 2006 Tensilica Inc. |
| 11 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 12 | * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson |
| 13 | * |
| 14 | * Chris Zankel <chris@zankel.net> |
| 15 | * Joe Taylor <joe@tensilica.com> |
| 16 | */ |
| 17 | |
| 18 | #include <linux/signal.h> |
| 19 | #include <linux/errno.h> |
| 20 | #include <linux/ptrace.h> |
| 21 | #include <linux/personality.h> |
| 22 | #include <linux/resume_user_mode.h> |
| 23 | #include <linux/sched/task_stack.h> |
| 24 | |
| 25 | #include <asm/ucontext.h> |
| 26 | #include <linux/uaccess.h> |
| 27 | #include <asm/cacheflush.h> |
| 28 | #include <asm/coprocessor.h> |
| 29 | #include <asm/processor.h> |
| 30 | #include <asm/syscall.h> |
| 31 | #include <asm/unistd.h> |
| 32 | |
| 33 | extern struct task_struct *coproc_owners[]; |
| 34 | |
| 35 | struct rt_sigframe |
| 36 | { |
| 37 | struct siginfo info; |
| 38 | struct ucontext uc; |
| 39 | struct { |
| 40 | xtregs_opt_t opt; |
| 41 | xtregs_user_t user; |
| 42 | #if XTENSA_HAVE_COPROCESSORS |
| 43 | xtregs_coprocessor_t cp; |
| 44 | #endif |
| 45 | } xtregs; |
| 46 | unsigned char retcode[6]; |
| 47 | unsigned int window[4]; |
| 48 | }; |
| 49 | |
| 50 | #if defined(USER_SUPPORT_WINDOWED) |
| 51 | /* |
| 52 | * Flush register windows stored in pt_regs to stack. |
| 53 | * Returns 1 for errors. |
| 54 | */ |
| 55 | |
| 56 | static int |
| 57 | flush_window_regs_user(struct pt_regs *regs) |
| 58 | { |
| 59 | const unsigned long ws = regs->windowstart; |
| 60 | const unsigned long wb = regs->windowbase; |
| 61 | unsigned long sp = 0; |
| 62 | unsigned long wm; |
| 63 | int err = 1; |
| 64 | int base; |
| 65 | |
| 66 | /* Return if no other frames. */ |
| 67 | |
| 68 | if (regs->wmask == 1) |
| 69 | return 0; |
| 70 | |
| 71 | /* Rotate windowmask and skip empty frames. */ |
| 72 | |
| 73 | wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb)); |
| 74 | base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4); |
| 75 | |
| 76 | /* For call8 or call12 frames, we need the previous stack pointer. */ |
| 77 | |
| 78 | if ((regs->wmask & 2) == 0) |
| 79 | if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12))) |
| 80 | goto errout; |
| 81 | |
| 82 | /* Spill frames to stack. */ |
| 83 | |
| 84 | while (base < XCHAL_NUM_AREGS / 4) { |
| 85 | |
| 86 | int m = (wm >> base); |
| 87 | int inc = 0; |
| 88 | |
| 89 | /* Save registers a4..a7 (call8) or a4...a11 (call12) */ |
| 90 | |
| 91 | if (m & 2) { /* call4 */ |
| 92 | inc = 1; |
| 93 | |
| 94 | } else if (m & 4) { /* call8 */ |
| 95 | if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4), |
| 96 | ®s->areg[(base + 1) * 4], 16)) |
| 97 | goto errout; |
| 98 | inc = 2; |
| 99 | |
| 100 | } else if (m & 8) { /* call12 */ |
| 101 | if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4), |
| 102 | ®s->areg[(base + 1) * 4], 32)) |
| 103 | goto errout; |
| 104 | inc = 3; |
| 105 | } |
| 106 | |
| 107 | /* Save current frame a0..a3 under next SP */ |
| 108 | |
| 109 | sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS]; |
| 110 | if (copy_to_user(&SPILL_SLOT(sp, 0), ®s->areg[base * 4], 16)) |
| 111 | goto errout; |
| 112 | |
| 113 | /* Get current stack pointer for next loop iteration. */ |
| 114 | |
| 115 | sp = regs->areg[base * 4 + 1]; |
| 116 | base += inc; |
| 117 | } |
| 118 | |
| 119 | regs->wmask = 1; |
| 120 | regs->windowstart = 1 << wb; |
| 121 | |
| 122 | return 0; |
| 123 | |
| 124 | errout: |
| 125 | return err; |
| 126 | } |
| 127 | #else |
| 128 | static int |
| 129 | flush_window_regs_user(struct pt_regs *regs) |
| 130 | { |
| 131 | return 0; |
| 132 | } |
| 133 | #endif |
| 134 | |
| 135 | /* |
| 136 | * Note: We don't copy double exception 'regs', we have to finish double exc. |
| 137 | * first before we return to signal handler! This dbl.exc.handler might cause |
| 138 | * another double exception, but I think we are fine as the situation is the |
| 139 | * same as if we had returned to the signal handerl and got an interrupt |
| 140 | * immediately... |
| 141 | */ |
| 142 | |
| 143 | static int |
| 144 | setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs) |
| 145 | { |
| 146 | struct sigcontext __user *sc = &frame->uc.uc_mcontext; |
| 147 | struct thread_info *ti = current_thread_info(); |
| 148 | int err = 0; |
| 149 | |
| 150 | #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x) |
| 151 | COPY(pc); |
| 152 | COPY(ps); |
| 153 | COPY(lbeg); |
| 154 | COPY(lend); |
| 155 | COPY(lcount); |
| 156 | COPY(sar); |
| 157 | #undef COPY |
| 158 | |
| 159 | err |= flush_window_regs_user(regs); |
| 160 | err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4); |
| 161 | err |= __put_user(0, &sc->sc_xtregs); |
| 162 | |
| 163 | if (err) |
| 164 | return err; |
| 165 | |
| 166 | #if XTENSA_HAVE_COPROCESSORS |
| 167 | coprocessor_flush_release_all(ti); |
| 168 | err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp, |
| 169 | sizeof (frame->xtregs.cp)); |
| 170 | #endif |
| 171 | err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt, |
| 172 | sizeof (xtregs_opt_t)); |
| 173 | err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user, |
| 174 | sizeof (xtregs_user_t)); |
| 175 | |
| 176 | err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs); |
| 177 | |
| 178 | return err; |
| 179 | } |
| 180 | |
| 181 | static int |
| 182 | restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame) |
| 183 | { |
| 184 | struct sigcontext __user *sc = &frame->uc.uc_mcontext; |
| 185 | struct thread_info *ti = current_thread_info(); |
| 186 | unsigned int err = 0; |
| 187 | unsigned long ps; |
| 188 | |
| 189 | #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x) |
| 190 | COPY(pc); |
| 191 | COPY(lbeg); |
| 192 | COPY(lend); |
| 193 | COPY(lcount); |
| 194 | COPY(sar); |
| 195 | #undef COPY |
| 196 | |
| 197 | /* All registers were flushed to stack. Start with a pristine frame. */ |
| 198 | |
| 199 | regs->wmask = 1; |
| 200 | regs->windowbase = 0; |
| 201 | regs->windowstart = 1; |
| 202 | |
| 203 | regs->syscall = NO_SYSCALL; /* disable syscall checks */ |
| 204 | |
| 205 | /* For PS, restore only PS.CALLINC. |
| 206 | * Assume that all other bits are either the same as for the signal |
| 207 | * handler, or the user mode value doesn't matter (e.g. PS.OWB). |
| 208 | */ |
| 209 | err |= __get_user(ps, &sc->sc_ps); |
| 210 | regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK); |
| 211 | |
| 212 | /* Additional corruption checks */ |
| 213 | |
| 214 | if ((regs->lcount > 0) |
| 215 | && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) ) |
| 216 | err = 1; |
| 217 | |
| 218 | err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4); |
| 219 | |
| 220 | if (err) |
| 221 | return err; |
| 222 | |
| 223 | /* The signal handler may have used coprocessors in which |
| 224 | * case they are still enabled. We disable them to force a |
| 225 | * reloading of the original task's CP state by the lazy |
| 226 | * context-switching mechanisms of CP exception handling. |
| 227 | * Also, we essentially discard any coprocessor state that the |
| 228 | * signal handler created. */ |
| 229 | |
| 230 | #if XTENSA_HAVE_COPROCESSORS |
| 231 | coprocessor_release_all(ti); |
| 232 | err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp, |
| 233 | sizeof (frame->xtregs.cp)); |
| 234 | #endif |
| 235 | err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user, |
| 236 | sizeof (xtregs_user_t)); |
| 237 | err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt, |
| 238 | sizeof (xtregs_opt_t)); |
| 239 | |
| 240 | return err; |
| 241 | } |
| 242 | |
| 243 | |
| 244 | /* |
| 245 | * Do a signal return; undo the signal stack. |
| 246 | */ |
| 247 | |
| 248 | asmlinkage long xtensa_rt_sigreturn(void) |
| 249 | { |
| 250 | struct pt_regs *regs = current_pt_regs(); |
| 251 | struct rt_sigframe __user *frame; |
| 252 | sigset_t set; |
| 253 | int ret; |
| 254 | |
| 255 | /* Always make any pending restarted system calls return -EINTR */ |
| 256 | current->restart_block.fn = do_no_restart_syscall; |
| 257 | |
| 258 | if (regs->depc > 64) |
| 259 | panic("rt_sigreturn in double exception!\n"); |
| 260 | |
| 261 | frame = (struct rt_sigframe __user *) regs->areg[1]; |
| 262 | |
| 263 | if (!access_ok(frame, sizeof(*frame))) |
| 264 | goto badframe; |
| 265 | |
| 266 | if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) |
| 267 | goto badframe; |
| 268 | |
| 269 | set_current_blocked(&set); |
| 270 | |
| 271 | if (restore_sigcontext(regs, frame)) |
| 272 | goto badframe; |
| 273 | |
| 274 | ret = regs->areg[2]; |
| 275 | |
| 276 | if (restore_altstack(&frame->uc.uc_stack)) |
| 277 | goto badframe; |
| 278 | |
| 279 | return ret; |
| 280 | |
| 281 | badframe: |
| 282 | force_sig(SIGSEGV); |
| 283 | return 0; |
| 284 | } |
| 285 | |
| 286 | |
| 287 | |
| 288 | /* |
| 289 | * Set up a signal frame. |
| 290 | */ |
| 291 | |
| 292 | static int |
| 293 | gen_return_code(unsigned char *codemem) |
| 294 | { |
| 295 | int err = 0; |
| 296 | |
| 297 | /* |
| 298 | * The 12-bit immediate is really split up within the 24-bit MOVI |
| 299 | * instruction. As long as the above system call numbers fit within |
| 300 | * 8-bits, the following code works fine. See the Xtensa ISA for |
| 301 | * details. |
| 302 | */ |
| 303 | |
| 304 | #if __NR_rt_sigreturn > 255 |
| 305 | # error Generating the MOVI instruction below breaks! |
| 306 | #endif |
| 307 | |
| 308 | #ifdef __XTENSA_EB__ /* Big Endian version */ |
| 309 | /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ |
| 310 | err |= __put_user(0x22, &codemem[0]); |
| 311 | err |= __put_user(0x0a, &codemem[1]); |
| 312 | err |= __put_user(__NR_rt_sigreturn, &codemem[2]); |
| 313 | /* Generate instruction: SYSCALL */ |
| 314 | err |= __put_user(0x00, &codemem[3]); |
| 315 | err |= __put_user(0x05, &codemem[4]); |
| 316 | err |= __put_user(0x00, &codemem[5]); |
| 317 | |
| 318 | #elif defined __XTENSA_EL__ /* Little Endian version */ |
| 319 | /* Generate instruction: MOVI a2, __NR_rt_sigreturn */ |
| 320 | err |= __put_user(0x22, &codemem[0]); |
| 321 | err |= __put_user(0xa0, &codemem[1]); |
| 322 | err |= __put_user(__NR_rt_sigreturn, &codemem[2]); |
| 323 | /* Generate instruction: SYSCALL */ |
| 324 | err |= __put_user(0x00, &codemem[3]); |
| 325 | err |= __put_user(0x50, &codemem[4]); |
| 326 | err |= __put_user(0x00, &codemem[5]); |
| 327 | #else |
| 328 | # error Must use compiler for Xtensa processors. |
| 329 | #endif |
| 330 | |
| 331 | /* Flush generated code out of the data cache */ |
| 332 | |
| 333 | if (err == 0) { |
| 334 | __invalidate_icache_range((unsigned long)codemem, 6UL); |
| 335 | __flush_invalidate_dcache_range((unsigned long)codemem, 6UL); |
| 336 | } |
| 337 | |
| 338 | return err; |
| 339 | } |
| 340 | |
| 341 | |
| 342 | static int setup_frame(struct ksignal *ksig, sigset_t *set, |
| 343 | struct pt_regs *regs) |
| 344 | { |
| 345 | struct rt_sigframe *frame; |
| 346 | int err = 0, sig = ksig->sig; |
| 347 | unsigned long sp, ra, tp, ps; |
| 348 | unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; |
| 349 | unsigned long handler_fdpic_GOT = 0; |
| 350 | unsigned int base; |
| 351 | bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) && |
| 352 | (current->personality & FDPIC_FUNCPTRS); |
| 353 | |
| 354 | if (fdpic) { |
| 355 | unsigned long __user *fdpic_func_desc = |
| 356 | (unsigned long __user *)handler; |
| 357 | if (__get_user(handler, &fdpic_func_desc[0]) || |
| 358 | __get_user(handler_fdpic_GOT, &fdpic_func_desc[1])) |
| 359 | return -EFAULT; |
| 360 | } |
| 361 | |
| 362 | sp = regs->areg[1]; |
| 363 | |
| 364 | if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) { |
| 365 | sp = current->sas_ss_sp + current->sas_ss_size; |
| 366 | } |
| 367 | |
| 368 | frame = (void *)((sp - sizeof(*frame)) & -16ul); |
| 369 | |
| 370 | if (regs->depc > 64) |
| 371 | panic ("Double exception sys_sigreturn\n"); |
| 372 | |
| 373 | if (!access_ok(frame, sizeof(*frame))) { |
| 374 | return -EFAULT; |
| 375 | } |
| 376 | |
| 377 | if (ksig->ka.sa.sa_flags & SA_SIGINFO) { |
| 378 | err |= copy_siginfo_to_user(&frame->info, &ksig->info); |
| 379 | } |
| 380 | |
| 381 | /* Create the user context. */ |
| 382 | |
| 383 | err |= __put_user(0, &frame->uc.uc_flags); |
| 384 | err |= __put_user(0, &frame->uc.uc_link); |
| 385 | err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]); |
| 386 | err |= setup_sigcontext(frame, regs); |
| 387 | err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); |
| 388 | |
| 389 | if (ksig->ka.sa.sa_flags & SA_RESTORER) { |
| 390 | if (fdpic) { |
| 391 | unsigned long __user *fdpic_func_desc = |
| 392 | (unsigned long __user *)ksig->ka.sa.sa_restorer; |
| 393 | |
| 394 | err |= __get_user(ra, fdpic_func_desc); |
| 395 | } else { |
| 396 | ra = (unsigned long)ksig->ka.sa.sa_restorer; |
| 397 | } |
| 398 | } else { |
| 399 | |
| 400 | /* Create sys_rt_sigreturn syscall in stack frame */ |
| 401 | |
| 402 | err |= gen_return_code(frame->retcode); |
| 403 | ra = (unsigned long) frame->retcode; |
| 404 | } |
| 405 | |
| 406 | if (err) |
| 407 | return -EFAULT; |
| 408 | |
| 409 | /* |
| 410 | * Create signal handler execution context. |
| 411 | * Return context not modified until this point. |
| 412 | */ |
| 413 | |
| 414 | /* Set up registers for signal handler; preserve the threadptr */ |
| 415 | tp = regs->threadptr; |
| 416 | ps = regs->ps; |
| 417 | start_thread(regs, handler, (unsigned long)frame); |
| 418 | |
| 419 | /* Set up a stack frame for a call4 if userspace uses windowed ABI */ |
| 420 | if (ps & PS_WOE_MASK) { |
| 421 | base = 4; |
| 422 | regs->areg[base] = |
| 423 | (((unsigned long) ra) & 0x3fffffff) | 0x40000000; |
| 424 | ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) | |
| 425 | (1 << PS_CALLINC_SHIFT); |
| 426 | } else { |
| 427 | base = 0; |
| 428 | regs->areg[base] = (unsigned long) ra; |
| 429 | } |
| 430 | regs->areg[base + 2] = (unsigned long) sig; |
| 431 | regs->areg[base + 3] = (unsigned long) &frame->info; |
| 432 | regs->areg[base + 4] = (unsigned long) &frame->uc; |
| 433 | regs->threadptr = tp; |
| 434 | regs->ps = ps; |
| 435 | if (fdpic) |
| 436 | regs->areg[base + 11] = handler_fdpic_GOT; |
| 437 | |
| 438 | pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n", |
| 439 | current->comm, current->pid, sig, frame, regs->pc); |
| 440 | |
| 441 | return 0; |
| 442 | } |
| 443 | |
| 444 | /* |
| 445 | * Note that 'init' is a special process: it doesn't get signals it doesn't |
| 446 | * want to handle. Thus you cannot kill init even with a SIGKILL even by |
| 447 | * mistake. |
| 448 | * |
| 449 | * Note that we go through the signals twice: once to check the signals that |
| 450 | * the kernel can handle, and then we build all the user-level signal handling |
| 451 | * stack-frames in one go after that. |
| 452 | */ |
| 453 | static void do_signal(struct pt_regs *regs) |
| 454 | { |
| 455 | struct ksignal ksig; |
| 456 | |
| 457 | task_pt_regs(current)->icountlevel = 0; |
| 458 | |
| 459 | if (get_signal(&ksig)) { |
| 460 | int ret; |
| 461 | |
| 462 | /* Are we from a system call? */ |
| 463 | |
| 464 | if (regs->syscall != NO_SYSCALL) { |
| 465 | |
| 466 | /* If so, check system call restarting.. */ |
| 467 | |
| 468 | switch (regs->areg[2]) { |
| 469 | case -ERESTARTNOHAND: |
| 470 | case -ERESTART_RESTARTBLOCK: |
| 471 | regs->areg[2] = -EINTR; |
| 472 | break; |
| 473 | |
| 474 | case -ERESTARTSYS: |
| 475 | if (!(ksig.ka.sa.sa_flags & SA_RESTART)) { |
| 476 | regs->areg[2] = -EINTR; |
| 477 | break; |
| 478 | } |
| 479 | fallthrough; |
| 480 | case -ERESTARTNOINTR: |
| 481 | regs->areg[2] = regs->syscall; |
| 482 | regs->pc -= 3; |
| 483 | break; |
| 484 | |
| 485 | default: |
| 486 | /* nothing to do */ |
| 487 | if (regs->areg[2] != 0) |
| 488 | break; |
| 489 | } |
| 490 | } |
| 491 | |
| 492 | /* Whee! Actually deliver the signal. */ |
| 493 | /* Set up the stack frame */ |
| 494 | ret = setup_frame(&ksig, sigmask_to_save(), regs); |
| 495 | signal_setup_done(ret, &ksig, 0); |
| 496 | if (test_thread_flag(TIF_SINGLESTEP)) |
| 497 | task_pt_regs(current)->icountlevel = 1; |
| 498 | |
| 499 | return; |
| 500 | } |
| 501 | |
| 502 | /* Did we come from a system call? */ |
| 503 | if (regs->syscall != NO_SYSCALL) { |
| 504 | /* Restart the system call - no handlers present */ |
| 505 | switch (regs->areg[2]) { |
| 506 | case -ERESTARTNOHAND: |
| 507 | case -ERESTARTSYS: |
| 508 | case -ERESTARTNOINTR: |
| 509 | regs->areg[2] = regs->syscall; |
| 510 | regs->pc -= 3; |
| 511 | break; |
| 512 | case -ERESTART_RESTARTBLOCK: |
| 513 | regs->areg[2] = __NR_restart_syscall; |
| 514 | regs->pc -= 3; |
| 515 | break; |
| 516 | } |
| 517 | } |
| 518 | |
| 519 | /* If there's no signal to deliver, we just restore the saved mask. */ |
| 520 | restore_saved_sigmask(); |
| 521 | |
| 522 | if (test_thread_flag(TIF_SINGLESTEP)) |
| 523 | task_pt_regs(current)->icountlevel = 1; |
| 524 | return; |
| 525 | } |
| 526 | |
| 527 | void do_notify_resume(struct pt_regs *regs) |
| 528 | { |
| 529 | if (test_thread_flag(TIF_SIGPENDING) || |
| 530 | test_thread_flag(TIF_NOTIFY_SIGNAL)) |
| 531 | do_signal(regs); |
| 532 | |
| 533 | if (test_thread_flag(TIF_NOTIFY_RESUME)) |
| 534 | resume_user_mode_work(regs); |
| 535 | } |